rTMS for OCD that has not responded to exposure therapy: the trial is running, the answer is not in

Design

Multicentre, randomised, sham-controlled trial protocol with parallel cost-effectiveness analysis

Population

250 adults with OCD and inadequate response to first-line treatment; 201 enrolled as of February 2026

Primary outcome

Y-BOCS severity at end of treatment (20-28 sessions of ERP plus active or sham 1 Hz pre-SMA rTMS)

Effect

Not reported — post-treatment assessments complete December 2026, 12-month follow-up into 2027

About half of adults with obsessive-compulsive disorder do not get an adequate result from exposure and response prevention (ERP), with or without a serotonin reuptake inhibitor. Between that and deep brain stimulation there is a wide gap, and repetitive transcranial magnetic stimulation (rTMS) has been sitting in it for years on the strength of small, mixed trials.

The TETRO protocol sets out what the authors describe as the first adequately powered randomised test: 250 adults with inadequate response to first-line treatment, randomised to ERP plus either active or sham 1 Hz rTMS over the pre-supplementary motor area, four sessions weekly for at least five weeks. The primary outcome is Y-BOCS severity at the end of treatment, with follow-up to 12 months and a parallel cost-effectiveness analysis — the latter because rTMS is reimbursed for depression in the Netherlands but not for OCD.

What to do with this today is mostly to hold the line. As of February 2026 recruitment stood at 201 of 250, post-treatment assessment finishes in December 2026, and the one-year follow-up runs into 2027. If a patient or family asks about rTMS for refractory OCD, the accurate answer is that it is plausible, being tested properly for the first time, and not yet supported well enough to recommend outside a trial. In India it is also largely a self-funded private-sector procedure, which makes the honesty more important, not less.

• Confirm the ERP was adequate before calling OCD treatment-resistant: dose, duration, in-session exposure, homework adherence.
• Check the SRI trial was at a genuine anti-obsessional dose and length before escalating.
• Describe rTMS for OCD as investigational when counselling — the depression evidence does not transfer.
• Note the target here is pre-SMA at 1 Hz, not the dorsolateral prefrontal protocol used in depression.
• Where cost is being discussed, be explicit that no efficacy readout exists yet.

Why it matters

It sets a date after which 'we don't know' stops being the honest answer — and that date is not yet.

Don't overread it

A protocol reports no outcomes; it is a statement of intent, not evidence of benefit.

The statistics, in plain English

There are no efficacy results to report. This is a protocol paper: it describes what will be measured and in whom. The only numbers available are administrative — 201 of a planned 250 participants enrolled as of February 2026. Any effect size quoted for this question today comes from earlier, smaller trials, which is precisely why an adequately powered trial was thought necessary.

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